1. Field of Invention
The present invention relates to an automatic ligation tool, and more specifically, to an automatic ligation tool capable of fastening ligature wire to an orthodontic bracket using a driving apparatus.
2. Description of Related Art
One of the important functions of orthodontics is to correct irregular arrangements of teeth in the dental arch. The is conventional technique for correcting such irregular arrangements of teeth includes the use of mounting a metal arch wire with a bracket an each tooth. Corrective forces are then imparted to selected teeth by means of ligature wires, springs and tensioning devices including elastic ligatures in the form at elastic O-rings and the like.
Generally, as can be seen in FIG. 1, an orthodontic bracket is composed of a base 31, a slot 32a, an identification mark 34, and a stem 32 having tie wing 32b. The base 31 is slightly larger than the center section of the bracket 102 and is concave to conform to the surface of the patient's tooth. The slot 32a is slightly angled to the horizontal center line of the bracket 102 to receive an arch wire 33 which makes an ideal dentition. The tie wing 32b is of rhomboidal construction and is used for securing and coming in contact with a ligature wire 35. The identification mark allows an orthodontist quicker identification when rebinding a loose bracket. The ligature wire 35 holds the arch wire 33 which makes an ideal dentition after the bracket 102 is set to the patient's teeth. The stem is an integral part of the base 31, which receives the ligature wire 35 or an elastic ligature.
As more clearly shown FIG. 2B a ligature wire 42, to be fastened to the bracket 102, has an elongated portion to receive and fix the arch wire, and a rectangular or oblong portion to receive the bracket. In fastening the ligature wire 42 to the bracket 102 to impart corrective forces, the steps for operating the ligature wire 42 are as follows: the first step is to grasp the end portion of the ligature wire 42 and to mount the rectangular portion on the stem formed between the tie wings 32a and the base 31; and the second step is to stretch the ligature wire 42 and rotate the end portion about 10 to 13 times. Therefore, in order to fasten such ligature wires to the bracket, an orthodontic ligature plier 41 known in the prior art has been used, as shown in FIG. 2A.
However, the prior art system for fastening the ligature wire by means of the aforementioned ligature plier has problems in that the operator easily fatigues when he fastens a lot of ligature wires to the brackets, and it takes the operator a lot of time to rotate each ligature wire by using the ligature plier. To overcome these disadvantages of the prior art of fastening the ligature wire to the bracket by means of the ligature plier, the dentist attaches the elastic ligature 43 onto the stem of the bracket, as shown in FIG. 2C. The elastic ligature 43 fastens the bracket 102 to the arch wire 33. The elastic ligature 43 having a high friction coefficient, however, hinders the bracket 102 from moving along the arch wire 33. Also, the elastic ligature 41 will change its color in an oral cavity and decrease its elasticity with the absorption of moisture.
The present invention provides an automatic ligation tool which overcomes the above mentioned problems of the prior art system for attaching the bracket. The automatic ligation tool according to the present invention allows the dentist to comfortably and quickly fasten the ligature wire to the bracket, and will serve well in the orthodontic field.